Electric battery.



v UNITED STATES PATENT orrios.

NEWCOMB K. CHANEY, OF LAKEWOOD, OHIO, ASSIGNOR T0 NATIONAL CARBON COMPANY, INC., A CORPORATION OF NEW YORK.

ELECTRIC BATTERY.

Patented Jan. 21, 1919.

No Drawing. Original application filed June 7, 1916, Serial No. 102,193. Divided and this application filed June 17, 1918. Serial No. 240,464.

teries, of which the following is a full, clear,

and exact description.

This invention relates'to electric batteries and is especially applicable to so-called dry cells.

Dry o'ells consist of a zinc can electrode in.

which is compacted an intimate mixture or mix as it is called, of carbon and manganese peroxid, usually pyrolusite, more or less dampened with ammomum chlorid electrolyte. The zinc can is separated from the mixture by a bibulous lining, usually paper, which permits the electrolyte to reach 1t but prevents theinsoluble constituents from passing through.

A common defect 1n dry cells is the corrosion of the zinc, regardless of whether the circuit is closed or not. I have made extensive experiments to determine the cause of such corrosion, and find that it is chiefly due to impurities'in the mix. I have discovered that iron salts and sulfids in the granular carbon, and soluble material from the pyrolusite, are the constituents chiefly responsible for the corrosive action. To eliminate such materials I have leached them with the electrolyte to be used in the cell, and then. after washing. have incorporated the purified materials in a dry cell, The open circuit voltage and short circuit current are increased by this treatment and shelf life tests have demonstrated that corrosion is very markedly decreased.

Since the electrolyte would be an expensive reagent to use for purification of the mix, I use preferably a m1neral ac1d such as sulfuric, nitric or hydrochloric acld. to accomplish the same purpose. If one considers the iron sulfid as the harmful constituent, its deleterious effect may be nullified by dissolving it from the mix or by oxidizing it to insoluble compounds.

In accordance with the first process, hydrochloric or other acid may be used to react on the impurity in accordance with the following equation;

In an electrolyte of ammonium chlorid and zinc chlorid, such as is used in' dry cells, any ferric salt will be decomposed and precipitated as insoluble Fe(OH),. Hence it is only necessary to get the ferroussulfid in solution and-oxidize the iron to the ferric condition, to render it insoluble and harmless under normal dry cell conditions. Similarly, such hydrogen sulfid as does not escape will be changed to insoluble free sulfid:

It is not. absolutely necessary to use an acid solvent as described. since ferrous sulfid is soluble in the usual dry cell electrolyte of ammonium chlorid and zinc chlorid, and it will be oxidized by acting upon the cell mix with an oxidizing agent. Other solvents may also be used to dissolve the impurities preliminary to acting upon them with oxidizing agents.

Instead of removing the iron sulfid by the process previously set forth, this can be accomplished by spreading carbon and manganese peroxid moistened, for example, with dilute acid, in thin layers where it will be exposed to currents of warm air. The manganese peroxid being an oxidizing agent, reacts on the acid mixture in the same way as the chlorin previously referred to. The purpose of spreading the mass in thin layers is to utilize the oxygen of the air as a further oxidizing means. Also, to increase the ac tion the materials may be, heated to, say

' oxid insufiicient quantities to the cell mix The purlfication likewise can be accomplished by passing soluble or gaseous oxidizin'g agents around the carbon and manganese peroxid particles until the sulfid is oxidized to harmless forms. -.As examples of such agents I may mention potassium permanganate, hydrogen peroxid, bleaching powder, c'hlorin, io d-in e'tcl The oxidizing materials should not be used in excess of the amount required by the reaction, or else the excess should be removed from the mix before placing it in the cell, but this will be readily accomplished by sufficient Washing with water after which the material should be dried.

In case that hydrochloric acid is used to decompose the impurities, it ispreferable to neutralize the surplus acid by adding zinc rather than to remove it. lhe hydrochloric acid will react with the oxid to produce Water and zinc chlorid which are necessary ingredients of the cell. 7

Cells made up of purified pyrolusite and carbon show an increased voltage of about marked increase in shelf life.

The improvement in the characteristics of the dry cell, I believe, is due to the re- 'moval of ferrous sulfid aspreviously mentioned, and of certain impurities in the phyrolusite, although I have determined that ferrous and sulfid ions each have a detrimental effect on the dry cell, regardless of the salt or material from which the ions may have dissociated.

This case is a division of my application filed June 7, 1916, Serial No. 102,193.

Having described my invention, what I claim is: I

1. A dry cell mix containing carbon free from soluble sulfids.

2. A dry cell mix containing carbon free from ferrous sulfids.

3. A dry cell mix containing carbon and an electrolyte of ammonium and zinc chlorid, said mix being free from ferrous sulfids.

In testimony whereof, I hereunto afiix my signature.

NEwCoMB KfCHANEY. 

